Modern communication is based upon commonly used communication standards and protocols. In many cases a communication protocol that was designed for a certain purpose is eventually used for other purposes. The Internet Protocol and the Ethernet are good examples of communication protocols that are used for various services that were not supported by these protocols when they first emerged to the market.
Different services or application are characterized by different requirements. For example the transmission of data differs from the transmission of time sensitive traffic such as voice or video.
In order to allow application of different types to be served by one protocol or one protocol suit, various quality of service mechanisms were developed. An article titled “Comparative Qos Technologies” by U4EA technologies, at www.u4eatech.com, describes the following quality of service mechanisms: First In First Out (also known as best effort), Priority Queuing, Custom Queuing, Weighted Fair Queuing (WFQ), Class Based Weighted Fair Queuing (CBWFQ), Low Latency Queuing (LLQ), Random Early Detection (RED), Weighted Random Early Detection (WRED), TCP Rate Control, Head On the Line (HOL), Partial Buffer Sharing (PBS), Token Bucket and Tail Drop. It is noted that some of these techniques are used for arbitration and some for rate shaping.
The following U.S. patents, all being incorporated herein by reference, provide a brief description of some prior art scheduling schemes: U.S. Pat. No. 6,262,986 of Oba et al., titled “Method and apparatus for packet scheduling using queue length and connection weight and U.S. Pat. No. 6,359,884 of Vinvent, titled “Modular scalable packet scheduler with rate based shaping and virtual port scheduler”.
There is a need to provide an efficient method and device for scheduling a transmission of packets.